Air conditioning device with reheat means



July 29, 1958 D. A. BAUER 2,

AIR CONDITIONING DEVICE WITH REHEAT MEANS Filed March 16, 1955 3Sheets-Sheet 1 &

:IMIMMMI- 54 DOA/A10 ,4. 15/41/52. IN VEN TOR. I

AIR CONDITIONING DEVICE WITH REHEAT MEANS Filed March 16, 1955 D. A.BAUER July 29,1958

3 Sheets-Sheet 2 wzz Don 440 A. 544/52.

INVENTOR.

July 29, 1958, D/A. BAUER 2,844,946

AIR CONDITIONING DEVICE WITH REHEAT MEANS Filed March 16, 1955 3Sheets-Sheet 3 A26 A76 A52 flan/4.4.0 A, 54052.

yl'g. z INVENTOR.

United States Patent AIR CONDITIONING DEVICE WITH REHEAT MEANS Donald A.Bauer, Michigan City, Ind. Application March 16, 1955, Serial No.494,745 1 Claim. (Cl. 62-173) This invention relates to improvements inair 'conditioning devices and methods.

The primary object of this invention is to provide a device and methodof this character in which air cooling means and air reheating means areassociated through suitable controls to operate upon a refrigeratingmedium for the purpose of maintaining a desired temperature within aspace to be conditioned.

A further object is to provide a device of this character having acooler operative to cool air and to reduce the humidity of air, andreheating means operative by the same medium employed in the coolingmeans, and adapted to temper or warm air which has been cooledexcessively incident to operation of the cooler to reduce humidity ofthe air to desired level.

A further object is to provide a device of this character having acooling coil unit and a heating coil unit positioned in the path of airdrawn through the system by a fan, said cooling and heating units beingoperative by means of a refrigerating agent which discharges from thecooling unit to a compressor and a condenser for return to the coolingunit, and a portion of which may be diverted in its flow from thecompressor to bypass through the reheating coil to deliver heat absorbedfrom the air in the cooling unit back to the air passing through thereheating unit.

A further object is to provide a device of this character having acooling coil, a heating coil, a compressor and a condenser, with meansresponsive to air temperature in the space to be conditioned, adapted todivert any selected portion of a refrigerant discharged from thecompressor to cause it to flow through the reheating coil to restore airtemperature to desired condition without requiring the operation of anauxiliary heating unit for the purpose and in a manner to effect asaving of the amount of cooling water normally required in a watercooled condenser for condensing a refrigerating agent after the same hasbeen compressed.

A further object is to provide a device ofthis character which isadapted to control the temperature of air at a constant comfortablevalue without substantial variation in rate of flow.

A further object is to provide a device of this character which iscapable of cooling and dehumidifying air at one hundred percentcapacity, or dehumidifying aloneat one hundred percent of capacity whilecooling to any desired extent between zero and one hundred percent ofcapacity.

Other objects will be apparent from the following specification.

In the drawings:

Fig. l is a schematic view illustrating one embodiment of the invention;

Fig. 2 is an axial sectional view of a diverter valve employed in thedevice;

Fig. 3 is a perspective view of a shiftable plug element of the valve;

Fig. 4 is an axial sectional view of the plug element of the valve;

' Fig. 5 is a schematic view illustrating another modification of theinvention;

Fig. 6 is a schematic view illustrating athird embodiment of theinvention; and

Fig. 7 is an axial sectional view of another valve construction.

Referring to the drawing, and particularly to Fig. 1

which illustrates one embodiment'of the invention, the

numeral 10 designates a passageway through which air is drawn by meansof a fan 12 operated by a motor 14 under suitable control in the mannerwell understood in the art. One or more filter elements 16 willpreferably span the passage 10 and will be removably mounted therein. Acooling coil 18, commonly referred to as a direct expansion coil, ismounted in the passage 10. A reheat coil 20 is also mounted in thepassage 10 and preferably is located between the direct expansion coil18 and the discharge end of the passage 10, as illustrated. The directexpansion coil 18 will be provided with an expansion valve 19 connectedin a line 22 leading from'a condenser and receiver unit 24 of anysuitable character, such as a combination water cooled condenser andreceiver of the type well known in the art. A suction line 26 connectsthe discharge end of the expansion coil 18 with a compressor 28. A gasdischarge line 30 leads from the compressor 28 to a valve 32, and a line34 leads from valve 32 to the condenser 24. I

A refrigerating agent or medium of any suitable type well known in theart, one example of which is Freon, is employed in the system. Arefrigerant in condensed state passes from the condenser 24 through theconduit 22 to the expansion valve 19 and thence through the directexpansion coil 18 which is impinged by the air flowing through thepassage 10 and thereby is cooled by delivering its heat to therefrigerant to gasify the same within the direct expansion coil 18. Thegas from coil 18 is drawn therefrom through the conduit '26 by theoperation of the compressor which serves to increase the pressure of therefrigerant. The high pressure refrigerant is dis charged from thecompressor 28 through the conduit 30 and the line 34 for delivery to thecondenser 24. The operation of the refrigerating unit of the devicefurther entails condensation of moisture in the air passing through thedevice upon contact thereof with the direct expansion coil 18. Thismoisture precipitates to a collector vessel 36 and is discarged througha drain 38.

A conduit 40 extends from the valve 32 to the reheat coil 20 at theendof that coil adjacent the airdischarge, high pressure gas which isdiverted by the valve 32 into the conduit 40 thus enters the reheat coil20 and flows therethrough in a counterflow direction compared to thedirection of flow of air within the chamber 10. The conduit 42 isconnected with the opposite end of the reheat coil 20 and is tapped orconnecte d to the conduit 34 between the valve ,32 and the condenser 24.The air in casing 10, which has been cooled by the direct e xpansioncoil 18, picks up heat from the reheat coil 20 with incidentcondensation of the refrigerant which then passes through the conduit42'and into the condenser 24.

Control of the device is effected in any suitable manner, as through athermostatic element 44, controlling a switch 46 "in the leads to areversible motor 48 for positioning the valve element of valve 32 withwhich the motor shaft 50 is connected. The arrangement willbe such thatthe valve 32 will be positioned 'to direct all of the high pressure gaspassing through conduit 30 to the conduit 34 when the ambienttemperature to which the thermostat 44 responds exceeds a predeterminedsetting. When ambient temperature falls below the predetermined setting,the thermostat operates the valve 46' to reverse the controlling orpositioning motor 48 to open the valve for the purpose' of dividing thehigh pressure gas led thereto-by the conduit 30 so that a predeterminedportion thereofmay passthrough conduit 40 to the reheat coilzothroughiwhich 'it circulates for ultimate return through line 42 tothe conduit 34 leading to the condenser 24. The rate of flow of gas tothe reheat coil 20, and the duration of such flow, is directlycontrolled by the thermostat 44 through the medium of the positioningmotor 48, and as soon as ambient temperature again raises to the desiredvalue for which the thermostat is set, the thermostat will operate theswitch 46 to control the positioning motor 48 for movement to a positionclosing the line 40.

By reason of the fact that the refrigerating agent, and particularlyFreon, is highly susceptible of leakage, a construction of the divertervalve 32 is important. One form of valve which I have found suitable isillustrated in Figs. 2, 3 and 4. The valve 32 has a body 52 having apassage 54 with which the conduit 30 communicates. A tapered or frustoconical valve seat portion 56 communicates with the passage '4 and acomparatively large bore portion 58 is open at the opposite end of thehousing 52. A cross-bore 60 with which conduit 34 communicates branchesfrom the tapered valve seat 56 intermediate the length thereof andcross-bore 62, with which conduit 40 communicates, likewise branchesfrom valve seat 56 intermediate the length thereof. A centrallyapertured closure plate 64 spans the open end of the valve housing towhich it is secured by screws or other securing means 66 and with whichit is sealed by gasket means 68. A packing gland 70 is seated in theaperture of the plate 64 and encircles and sealingly engages the motorshaft 50. A valve element 72 is carried by shaft 50, the same beingfrusto conical in general outline and adapted for a snug rotative fitwithin the tapered valve seat 55 to which it is urged by the coil spring74.

The valve element 72 is best illustrated in Figs. 3 and 4 andconstitutes a disk portion 76 at its large diameter end and a diskportion 78 at its small diameter end, the same being spaced apart andinterconnected by a longitudinal portion 80 defined by cutting awayapproximately one-half of the plug between the portions 76 and 78 alongthe plane 82. An aperture 84 is formed in the disk 78 and the face 82 ispreferably recessed at 86 in register with the aperture 84 toaccommodate full and substantially unrestricted flow from conduit intothe space between the disk portions 76 and 78. The longitudinal portion80 is of sufiicient extent to span and completely close thecross-passage 62 leading to the conduit in one position of the valveelement, namely, the position occurring when ambient temperature exceedsthe temperature for which the thermostat 44 is set. Rotation of thevalve element from that position to a position, such as illustrated inFigs. 2 and 4, will permit at least partial communication or opening ofeach of the passages 60 and 62. Rotation of the valve serves aproportioning function regulating or proportioning the percentage of gasentering the valve through the conduit 30 which passes to each of theconduits 34 and 40. Thus, when ambient temperature falls below thetemperature for which the thermostat 44 is set, the valve will be set topermit a part of the gas from conduit 30 to pass through conduit 40.Likewise, the greater the temperature drop at the thermostat, thegreater the extent to which the valve opens into communication with theconduit 40.

Control of the valve 32 from the thermostat 44 can occur independentlyof any variation of the rate of flow of air through the passage 10eifected by operation of the fan 12. Thus a substantially constant flowof air can occur, and the heating and cooling thereof can vary withoutvarying the rate of air flow.

A modified embodiment of the invention is illustrated schematically inFig. 5. In this construction a housing or passage 90 open for passage ofair therethrough by a fan or like means has a direct expansion coil 92and a reheating coil 94 positioned therein in sequence. Air

will be taken from the space to be conditioned and passed through themember to be sequentially acted upon by the direct expansion or coolingcoil 92 and the reheating coil 94 and then returned or delivered to thespace to be conditioned. A condenser 96 and a compressor 98 areconnected with the coils 92 and 94 to accommodate circulation of Freonor other refrigerating agent therethrough.

A conduit 100 leads from the condenser 96, which may be of any suitabletype and which preferably is a water cooled condenser or receiver, tothe expansion valve 102 of the direct expansion coil 92. The conduit 100delivers the refrigerant in liquid form to the coil 92 in which therefrigerant is exposed to flow of warm air through the passage 90 andpicks up heat from the air and thereby becomes gasified. The gasifiedrefrigerant is discharged from the coil 92 at a suction line 104 leadingto the intake of the compressor 98. The compressor 98 serves to compressthe gas from a low pressure state in which it exists in the coil 92, forexample, at a pressure of approximately thirty-seven pounds per squarefoot, to a pressure which is much greater, for example, pressure in theorder of 105 pounds per square foot. The operation of the compressorserves to draw the gas from the coil 92 and thus produces the flow inthe system.

Gas at high pressure which is discharged by the compressor 98 passesthrough the conduit 106 to a T-fitting 108 with which is connected aconduit 110 leading to the condenser 96. High pressure gas thus flowsfrom the compressor to the condenser through conduits 106 and 110.

A second conduit 112 branches from the T-fitting 108 and has amodulating valve 114 interposed therein. The modulating valve has acontrol or operating member 116 which may be a reversible modulatingmotor whose shaft 118 is connected to' the shiftable valve element ofthe valve 114. The modulating member 116 is under the influence of acontroller 120, such as a thermostatic switch, while the controller 120has been illustrated as located within the passage 90, it will beunderstood that this is not essential and that it may be located withinthe space to be conditioned. The conduit 112 leads to the reheat coil 94at the end thereof remote from the direct expansion coil 92. A conduit122 constitutes a discharge line leading from the reheat coil 94. Ashere illustrated, the discharge line 102 is connected at a T- fitting124 with the conduit 120 adjacent to the condenser 96'. If desired, theline 122 may lead to the condenser 96, as illustrated in Fig. 1.

The valve 114 employed in this construction is preferably of thecharacter illustrated in Fig. 7, having a cupshaped housing 117 whosebore has a tapered inner end portion 119 and a cylindrical bore portion121. Passages are formed in the body 117 transversely thereof tointersect the bore 119 at the tapered portion thereof preferablyintermediate the length of said tapered portion. A frusto conical valveelement 123 is rotatable in and has a snug fit in the tapered bore 119and has a passage 125 extending therethrough perpendicular to its axisand adapted for register with the passages which communicate withconduit 112. The valve element 123 is mounted upon the motor shaft 119which passes through an aperture in the end plate 126 of a screwthreadedcap fitting over and closing the open end of the cup-shaped housing 117.A plurality of packing members or washers 128 encircle the shaft 119 andefiect a seal around the shaft and at the bore 121. The washers 128 areclamped between an inner plate 130 and an outer plate 132 by means of acoil spring 13w which encircles the shaft 118 and preferably is heldspaced from said shaft by means of a bushing sleeve or tubularpositioning member 136.

This embodiment ofthe invention relies upon the afimity of hot gases forcooling surfaces and upon the fact that the condenser 96 will normallyoperate at a higher pressure than the pressure within the reheat coil 94to produce flow of gas through the conduit 112 to the extent permittedby the modulating valve 114. 'Consequently, in the operation of thisdevice, the natural flow path for the hot refrigerant gases dischargedfrom the compressor 98 is through the reheat coil 94 to the extent thatthe valve 114 permits flow of such gases therepast. This factor permitsthe use of the comparatively simple valve 114 illustrated in Fig. 7 andeliminates the necessity for a valve of the construction illustrated inFig. 2.

Another embodiment of the invention is illustrated in Fig. 6. In thisconstruction the air passage 150 receives the direct expansion coil 152and the reheat coil 154 shown schematically and arranged in sequencewith respect to the direction of air flow which is as indicated by thearrow.

The suction line 156 leading from the direct expansion coil 152 extendsto the compressor 158. Hot gases at high pressure discharged from thecondenser pass through conduit 160 to T-fitting 162, having conduit 16'4connected therewith and leading to condenser 166. The condenser 166 ispreferably of the counterflow water cooled type having a water coil 168whose inlet 170 is located adjacent the discharge end of the condenserand whose outlet 172 is located adjacent the inlet end of the condenser.The water coils 168 preferably pass through the gas coil 174 of thecondenser to provide cooling action upon the gas within the coil 174.

The direct expansion coil 152 is of the type having a plurality ofindividual coils, here shown as three coils 176, 178 and 180. The outletfrom the condenser 166 consists of a plurality of capillary tubes equalin number to the number of coils in the direct expansion coil unit 152.Thus as here shown, three capillary tubes 177, 179 and 181 branch fromthe discharge end of the gas conduit 174 of the condenser and extend inparallel relation for connection, respectively, to the coils 176', 178and 180. The capillary tubes will be of identical properties withrespect to size of bore and also with respect to the length thereof.

The reheat coil 154 will be connected at the end thereof remote from thedirect expansion coil 152 with a conduit 182 leading to the T-fitting162 and having modulating valve 184 interposed therein, and operated bythe shaft or other output member 186 of a controller 188, such as areversible motor which in turn operates in response to a control element190 responding to the ambient temperature or to the output temperatureor to any other property associated with the condition to be controlled.The valve 184 will operate to modulate and control the proportion of thehot gases discharged from the compressor 158 which passes to the reheatcoil 154. The discharge end of the reheat coil 154 has connected theretoa plurality of capillary tubes equal in number to the capillary tubesextending between the condenser and the direct expansion coil. Thusthree capillary tubes are here shown, consisting of tube 192 whichconnects with capillary tube 181 intermediate the latter, tube 194 whichconnects with capillary tube 179, and capillary tube 196 which connectswith capillary tube 177. The capillary tubes 192, 194 and 196 have thesame properties as the capillary tubes 177, 179 and 181. In other words,each has a bore similar to the bore of the others and to the bores ofthe other set, and each of the tubes 192, 194, 196 is exactly the samelength as the others, and also exactly of the same length as thecapillary tubes 177, 179 and 181 leading from the counterflow condenser.

Each of the three embodiments of the invention illustrated operates uponthe principle that a selected portion of high pressure refrigerant gasdischarged from the compressor is diverted from the line leading to thecondenser to be delivered to the reheating coil. This high pressure gashas a high temperature due to its compression and glue to theconcentration of heatat the compressor.

Consequently, as air flows through the device, it first is cooled at thedirect expansion coil and then is reheated at the reheating coil, whereheat transfer occurs with the air taking up heat from the refrigeratinggas in the reheating coil to the extent required or called for by thecontrol element which actuates the modulating valve in the line leadingto the reheat coil. Thus the gas which is discharged from the reheatcoil will have been cooled by heat transfer to the air and may bedirected either to the receiver of the condenser or to the line leadingto the direct expansion coil, as the demands of the system may require.

By this apparatus the air is cooled and also dehumidified.Moisture'contained in the air is condensed by the direct expansion coiland is drained therefrom. Subsequent reheating of the air at the reheatcoil does not embody or entail any humidifying effect so thatdehumidifying action of the system is eificient at all times and can beaccomplished in all settings of the controller, that is, in settingswhich require reheating of the air at the reheating coil in addition tosettings in whch the reheating coil is not operative because the controlelements call for a cooling effect equal to the capacity of the directexpansion coil.

The operation of the modulating control in the modulating valve respondsto temperature or to any condition selected for control purposes. Aconstant control is efiected so that, assuming a demand for coolingwhich results in shutting off flow to the reheat coil, and assumingfurther that this cooling proceeds beyond the extent required so that ahigher temperature is called for, the valve will modulate to permitenough hot gas to enter the reheat coil to effect the reheating requiredto raise the temperature to the desired point. Consequently, the controlsecured by the system utilizes any selected percentage of the coolingcapacity of the direct expansion coil required to maintain the selectedcondition. Thus it may be said that each of these devices operates tocontrol temperature through a range from zero percent to one hundredpercent of the cooling capacity of the direct expansion coil whilemaintaining at all times the dehumidifying action of the device at onehundred percent of the dehumidifying capacity of the coil tube.

While the preferred embodiments of the invention have been illustratedand described herein, it will be understood that changes in theconstruction may be made within the scope of the appended claims withoutdeparting from the spirit of the invention.

I claim:

An air conditioning device comprising a housing having an air inlet andan air outlet, 21 direct expansion coil, a reheat coil, said coils beingmounted in said housing in sequence, a compressor connected to saidexpansion coil, a condenser, a line connecting said condenser to saidcompressor, a line connecting said condenser and said direct expansioncoil, a line connected to said reheat coil and branching from the linebetween said compressor and condenser, a line connecting said reheatcoil to the line between said expansion coil and said condenser, amodulating valve in said branch line, and means responsive to a variablefor modulating said valve said expansion coll comprising a plurality ofsections, said second named line and said last named line cooperating todefine a supply of condensed refrigerant to said expansion coil dividedequally between said sections.

References Cited in the file of this patent UNITED STATES PATENTS1,837,798 Shipley Dec. 22, 1931 2,154,136 Parcaro Apr. 11, 19392,170,072 Hartig Aug. 22, 1939 2,257,975 Miller Oct. 7, 1941 2,515,842Swinburne July 18, 1950 2,679,142 McGrath May 25, 1954 2,702,456Ringquist Feb. 22, 1955

